Editors note: This morning we failed to live up to our promise, and Google App Engine applications experienced increased latencies and time-out errors. For a full report of the incident, visit the Google App Engine blog.

We know you rely on App Engine to create applications that are easy to develop and manage without having to worry about downtime. App Engine is not supposed to go down, and our engineers work diligently to ensure that it doesn’t. However, from approximately 7:30 to 11:30 AM US/Pacific today, about 50% of requests to App Engine applications failed.

During this incident, no application data was lost and application behavior was restored without any manual intervention by developers. There is no need to make any code or configuration changes to your applications.

We will proactively issue credits to all paid applications for ten percent of their usage for the month of October to cover any SLA violations. This will appear on applications’ November bills. There is no need to take any action to receive this credit.

We apologize for this outage, and in particular for its duration and severity. Since launching the High Replication Datastore in January 2011, App Engine has not experienced a widespread system outage. We know that hundreds of thousands of developers rely on App Engine to provide a stable, scalable infrastructure for their applications, and we will continue to improve our systems and processes to live up to this expectation.